There are many types of resets that you can do to your mobile phones. Soft reset and Hard reset. To soft reset you devices, you only need to power off and then power on your phone. No data is lost in the process. Otherhand In Hare reset a phone is reverted to its original settings and it cleans an os. It removes all the data and information stored in the device. Its also useful to those persons whose mobile is infected by Virus.